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<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>20-检测数据类型</title>
  </head>
  <body>
    <script>
      let num = 10
      console.log(typeof num)

      let str = 'pink'
      console.log(typeof str)

      let un
      console.log(typeof str)
    </script>
  </body>
</html>
